A fan system is used for dissipating heat of an electronic device. The fan system includes a fan, a hollow structure, and a control circuit. Sound waves made by the fan are transmitted to an interior of the hollow structure when the fan is operating. The control circuit is connected to the hollow structure and is configured to control deformation/deformations of the hollow structure according to a state/states of the fan and/or the electronic device, which change a volume of the interior of the hollow structure for making a resonance frequency of the hollow structure being approximate to a rotation speed of the fan or being the same as the rotation speed of the fan.

A two-way flow control device including: a housing defining a first opening interface and a second opening interface, a rotor having a plurality of blades, each blade controllable to be angled in a range of positive and negative blade angles to generate respective positive and negative flows between the first opening interface and the second opening interface, first stator vanes mounted to the housing between the blades and the first opening interface, each including a respective stator vane slope having a stator vane angle which are collectively positive or negative angled; second stator vanes mounted to the housing between the blades and the second opening interface, each including a respective stator vane slope having a stator vane angle which are collectively opposite angled to the stator vane angles of the first stator vanes, the second stator vanes mounted to be circumferentially offset with respect to the first stator vanes.

A noise reduction structure for a ventilation treatment device and the ventilation treatment device are provided. The noise reduction structure comprises a first micropore plate; the first micropore plate has a first plate surface and a second plate surface which are opposite to each other, the first plate surface is used for forming a first chamber; the second plate surface is used for forming an air passage such that air in the air passage flows along the second plate surface; the first micropore plate has a plurality of first micro-vias through which the first chamber communicates with the air passage. The noise reduction structure is wide in noise reduction frequency band, may effectively reduce aerodynamic noise in the air passage, and improves the satisfaction degree of a patient using the ventilation treatment device.

A gas turbine engine includes a fan rotor driven by a fan drive turbine about an axis through a gear reduction to reduce a speed of the fan rotor relative to a speed of the fan drive turbine. A fan case surrounds the fan rotor, and a core engine with a compressor section, including a low pressure compressor. The fan rotor delivers air into a bypass duct defined between the fan case and the core engine. A rigid connection is between the fan case and the core engine includes three triangular-frame connecting members rigidly connected to the fan case at a fan case connection point, and to the core engine at a core engine connection point. The triangular-frame connecting members each are defined by two rigid legs which extend between the fan case and to the core engine, along directions each have a component extending radially inwardly and a component in opposed circumferential directions to each other. A plurality of non-structural fan exit guide vanes and the non-structural fan exit guide vanes are provided with an acoustic feature to reduce noise. The non-structural fan exit guide vanes are rigidly mounted to at least one of the fan case and the core engine.

A modular fan cover assembly for inclusion on an electric motor is selectively configurable for degrees of reduced noise operation. The modular fan cover assembly includes a plurality of cooperating components arranged to direct fluid communication through the assembly. The components may include, for example, a fan cover defining a fan chamber for enclosing the fan, an inlet cover including an inlet chamber and a plurality of inlet apertures, and a silencing insert selectively includable with the fan cover assembly that may include one or more silencing features. The selective combination of the components can redirect airflow through various turns or bend in the modular fan cover assembly to trap or suppress noise propagating from the electric motor. The modular fan cover assembly may be operatively equipped with a blower assembly.

A silencing device and a compressor having the silencing device are disclosed. The silencing device has a housing. An air inlet and an air outlet are provided to the housing. An air flow channel is provided in the housing for allowing air communication between the air inlet and the air outlet. An oil hole is provided in the housing for discharging oil from the housing. An oil guide part is arranged on the outside of the housing and at a position downstream of the oil hole in the moving direction of the oil, such that the oil drips from the housing after flowing from the oil hole to the oil guide part.

A reference microphone for detecting noise is located under a first duct. The noise is in the form of a first plane wave in the first duct. A speaker is located on a top of the first duct. Connected to an upper part of the first duct is a second duct including an error microphone. The first plane wave in the first duct passes through an acoustic path and reaches the second duct. The error microphone detects the sound, and the speaker outputs a second plane wave with an opposite phase for canceling the first plane wave.

Provided is an axial flow blower capable of improving an intake efficiency even when air is introduced from a plurality of suction openings. An axial flow blower includes a housing including an air blowing passage extending from a plurality of suction openings (lateral suction opening and lower suction opening) to an ejection opening, an electric motor, and an air blowing fan that blows air from the plurality of suction openings (lateral suction opening and lower suction opening) toward the ejection opening. An air blowing guide member is provided closer to the plurality of suction openings (lateral suction opening and lower suction opening) than to the air blowing fan, inside of the plurality of suction openings (lateral suction opening and lower suction opening). The air blowing guide member guides air introduced into the air blowing passage from the plurality of suction openings (lateral suction opening and lower suction opening) toward the air blowing fan.

A vehicle heater includes a heater housing (12′), through which heating air to be heated can flow, with a heating air inlet area and with a heating air outlet area. A burner unit is arranged in the heater housing. A combustion air blower (46′) is arranged in the heater housing for delivering combustion air to the burner unit. A heat exchanger unit is arranged in the heater housing (12′). Heating air flowing through the heater housing (12′) can flow around the heat exchanger unit. A combustion air intake muffler (76) is arranged essentially in the heater housing (12′). A muffler housing (78) made in one piece with the heater housing (12′) is associated with the combustion air blower (46′).

A fan frame body structure includes a first frame body. The first frame body has a first upper end, a first lower end, a first frame wall and a first main flow way. The first main flow way passes through the first frame body and is formed with a first main inlet and a first main outlet respectively at the first upper end and the first lower end. A first subsidiary flow way is disposed in the first frame wall. The first subsidiary flow way is in parallel the first main flow way. The first subsidiary outlet is positioned at the first upper end of the first frame body in flush with and in adjacency to the first main inlet.